Introduction: The differential diagnosis of multiple sclerosis (MS) includes a wide variety of autoimmune diseases (systemic lupus erythematosus, Sjogren syndrome, antiphospholipid syndrome, etc.). The presence of antiphospholipid antibodies (APLA) in serum of MS patients has been reported to be as low as 10%, or sometimes as high as 88% of the cases, although its significance in the pathogenesis of the disease, or its diagnostic usefulness is still unknown. The goal of this study was to describe the clinic and demographic characteristics of a sample of patients with MS from the Hospital General de Mexico (HGM), as well as to determine the presence and frequency of APLA in cerebrospinal fluid (CSF) and serum samples of these patients. Patients and methods: A prospective study with patients from the Neurology Department at the HGM was performed. These patients were diagnosed with MS over a one-year period. Clinical and demographic characteristics were compiled. VDRL and anticardiolipin-beta 2GP-1 complex antibodies were analyzed in CSF and serum samples. Results: Twelve patients were included in the study, the majority females (58%). The predominant clinic feature was optic neuritis (66.6%) followed by medullary involvement (58%). Most of patients were ambulatory (<. 4 EDSS points). Auto-antibody levels were found in negative ranges in all cases, both in CSF and serum. Conclusions: The clinical-demographic characteristics in patients studied in this work were similar to those previously reported, and the levels of anti-cardiolipin-beta 2GP-1 were negative, thus indicating the existence of different clinical and demographic variables influencing their detection. (C) 2009 Sociedad Espanola de Neurologia. Published by Elsevier Espana, S.L. All rights reserved.